To produce yogurt, milk is first heated, usually to about 85 °C (185 °F), to denature the milk proteins so that they do not form curds. After heating, the milk is allowed to cool to about 45 °C (113 °F).[3] The bacterial culture is mixed in, and that temperature of 45 °C is maintained for 4 to 12 hours to allow fermentation to occur.[4]

Etymology and spelling

The word is derived from Turkish: yoğurt,[5] and is usually related to the verb yoğurmak, “to knead”, or “to be curdled or coagulated; to thicken”.[5] It may be related to yoğun, meaning thick or dense. The sound ğ was traditionally rendered as “gh” in transliterations of Turkish from around 1615–1625.[5] In modern Turkish the letter ğ marks a diaeresis between two vowels, without being pronounced itself, which is reflected in some languages’ versions of the word (e.g. Greek γιαούρτι giaoúrti, French yaourt, Romanian iaurt).

In English, the several variations of the spelling of the word include yogurt, yoghurt, and to a lesser extent yoghourt or yogourt.[5]

History

Analysis of the L. delbrueckii subsp. bulgaricus genome indicates that the bacterium may have originated on the surface of a plant.[6] Milk may have become spontaneously and unintentionally exposed to it through contact with plants, or bacteria may have been transferred from the udder of domestic milk-producing animals.[7] The origins of yogurt are unknown, but it is thought to have been invented in Mesopotamia around 5000 BC.[8] In ancient Indian records, the combination of yogurt and honey is called “the food of the gods”.[9] Persian traditions hold that “Abraham owed his fecundity and longevity to the regular ingestion of yogurt”.[10]

Some accounts suggest that Mughal Indian emperor Akbar‘s cooks would flavor yogurt with mustard seeds and cinnamon.[19] Another early account of a European encounter with yogurt occurs in French clinical history: Francis I suffered from a severe diarrhea which no French doctor could cure. His ally Suleiman the Magnificent sent a doctor, who allegedly cured the patient with yogurt.[19][20] Being grateful, the French king spread around the information about the food that had cured him.

Isaac Carasso industrialized the production of yogurt. In 1919, Carasso, who was from OttomanSalonika, started a small yogurt business in Barcelona, Spain, and named the business Danone (“little Daniel”) after his son. The brand later expanded to the United States under an Americanized version of the name: Dannon. Yogurt with added fruit jam was patented in 1933 by the Radlická Mlékárna dairy in Prague.[22]

Colombo Yogurt was originally delivered around New England in a horse-drawn wagon inscribed with the Armenian word “madzoon” which was later changed to “yogurt”, the Turkish language name of the product, as Turkish was the lingua franca between immigrants of the various Near Eastern ethnicities who were the main consumers at that time. Yogurt’s popularity in the United States was enhanced in the 1950s and 1960s, when it was presented as a health food by scientists like Hungarian-born bacteriologist Stephen A. Gaymont.[27] Plain yogurt still proved too sour for the American palate and in 1966 Colombo Yogurt sweetened the yogurt and added fruit preserves, creating “fruit on the bottom” style yogurt. This was successful and company sales soon exceeded $1 million per year.[28] By the late 20th century, yogurt had become a common American food item and Colombo Yogurt was sold in 1993 to General Mills, which discontinued the brand in 2010.[29]

Market and consumption

In 2017, the average American ate 13.7 pounds of yogurt and that figure has been declining since 2014.

Sale of yogurt was down 3.4 percent over the 12 months ending in February 2019. The decline of Greek-style yogurt has allowed Icelandic style yogurt to gain a foothold in the United States with sales of the Icelandic style yogurt increasing 24 percent in 2018 to $173 million.[30]

Tilde (~) represents missing or incomplete data.
The above shows little difference exists between whole milk and yogurt made from whole milk with respect to the listed nutritional constituents.

Because it may contain live cultures, yogurt is often associated with probiotics, which have been postulated as having positive effects on immune, cardiovascular or metabolic health.[33][34][35] But high-quality clinical evidence is insufficient to conclude that consuming yogurt lowers the risk of diseases or otherwise improves health.[36]

Varieties and presentation

Tzatziki or cacık is a meze made with yogurt, cucumber, olive oil and fresh mint or dill

Dahi is a yogurt from the Indian subcontinent, known for its characteristic taste and consistency. The word dahi seems to be derived from the Sanskrit word dadhi (“sour milk”), one of the five elixirs, or panchamrita, often used in Hindu ritual. Sweetened dahi (mishti doi or meethi dahi) is common in eastern parts of India, made by fermenting sweetened milk. While cow’s milk is considered sacred and is currently the primary ingredient for yogurt, goat and buffalo milk were widely used in the past, and valued for the fat content (see buffalo curd).

Dadiah or dadih is a traditional West Sumatran yogurt made from water buffalo milk, fermented in bamboo tubes.[37] Yogurt is common in Nepal, where it is served as both an appetizer and dessert. Locally called dahi, it is a part of the Nepali culture, used in local festivals, marriage ceremonies, parties, religious occasions, family gatherings, and so on. One Nepalese yogurt is called juju dhau, originating from the city of Bhaktapur. In Tibet, yak milk (technically dri milk, as the word yak refers to the male animal) is made into yogurt (and butter and cheese) and consumed.

In Northern Iran, Mâst Chekide is a variety of kefir yogurt with a distinct sour taste. It is usually mixed with a pesto-like water and fresh herb purée called delal. Common appetizers are spinach or eggplantborani, Mâst-o-Khiâr with cucumber, spring onions and herbs, and Mâst-Musir with wild shallots. In the summertime, yogurt and ice cubes are mixed together with cucumbers, raisins, salt, pepper and onions and topped with some croutons made of Persian traditional bread and served as a cold soup. is a warm yogurt soup with fresh herbs, spinach and lentils. Even the leftover water extracted when straining yogurt is cooked to make a sour cream sauce called kashk, which is usually used as a topping on soups and stews.

(cucumber and yogurt salad) is a dish in Lebanon and Syria. Also, a wide variety of local Lebanese and Syrian dishes are cooked with yogurt like “Kibbi bi Laban” , a creamy yogurt with much higher fat content (10%) than many yogurts offered in English-speaking countries. Dovga, a yogurt soup cooked with a variety of herbs and rice, is served warm in winter or refreshingly cold in summer. Jameed, yogurt salted and dried to preserve it, is consumed in Jordan. Zabadi is the type of yogurt made in Egypt, usually from the milk of the Egyptian water buffalo. It is particularly associated with Ramadan fasting, as it is thought to prevent thirst during all-day fasting.[38]

Sweetened and flavored

To offset its natural sourness, yogurt is also sold sweetened, sweetened and flavored or in containers with fruit or fruit jam on the bottom.[39] The two styles of yogurt commonly found in the grocery store are set-style yogurt and Swiss-style yogurt. Set-style yogurt is poured into individual containers to set, while Swiss-style yogurt is stirred prior to packaging. Either may have fruit added to increase sweetness.[40][41]

Lassi and moru are common beverages in India. Lassi is stirred liquified curd that is either salted or sweetened with sugar commonly, less commonly honey and often combined with fruit pulp to create flavored lassi. Mango lassi is a western favorite, as is coconut lassi. Consistency can vary widely, with urban and commercial lassis being of uniform texture through being processed, whereas rural and rustic lassi has curds in it, and sometimes has malai (cream) added or removed. Moru is a South Indian summer drink, meant to keep drinkers hydrated through the hot and humid summers of the South. It is prepared by considerably thinning down yogurt with water, adding salt (for electrolyte balance) and spices, usually green chili peppers, asafoetida, curry leaves and mustard.

Large amounts of sugar – or other sweeteners for low-energy yogurts – are often used in commercial yogurt. Some yogurts contain added modified starch,[42][43]pectin (found naturally in fruit), and/or gelatin to create thickness and creaminess artificially at lower cost. This type of yogurt is also marketed under the name Swiss-style, although it is unrelated to the way yogurt is eaten in Switzerland. Some yogurts, often called “cream line”, are made with whole milk which has not been homogenized so the cream rises to the top. In the UK, Ireland, France and United States, sweetened, flavored yogurt is common, typically sold in single-servingplastic cups. Common flavors include vanilla, honey, and toffee, and fruit such as strawberry, cherry, blueberry, blackberry, raspberry, mango and peach. In the early twenty-first century yogurt flavors inspired by desserts, such as chocolate or cheesecake, have been available.
There is concern about the health effects of sweetened yogurt, due to its high sugar content.

Straining

Strained yogurt has been strained through a filter, traditionally made of muslin and more recently of paper or non-muslin cloth. This removes the whey, giving a much thicker consistency. Strained yogurt is made at home, especially if using skimmed milk which results in a thinner consistency.[44] Yogurt that has been strained to filter or remove the whey is known as Labneh in Middle Eastern countries. It has a consistency between that of yogurt and cheese. It may be used for sandwiches in Middle Eastern countries. Olive oil, cucumber slices, olives, and various green herbs may be added. It can be thickened further and rolled into balls, preserved in olive oil, and fermented for a few more weeks. It is sometimes used with onions, meat, and nuts as a stuffing for a variety of pies or kibbeh balls.

Some types of strained yogurts are boiled in open vats first, so that the liquid content is reduced. The East Indian dessert, a variation of traditional dahi called mishti dahi, offers a thicker, more custard-like consistency, and is usually sweeter than western yogurts.[45] Strained yogurt is also enjoyed in Greece and is the main component of tzatziki (from Turkish “cacık“), a well-known accompaniment to gyros and souvlaki pita sandwiches: it is a yogurt sauce or dip made with the addition of grated cucumber, olive oil, salt and, optionally, mashed garlic. Srikhand, a dessert in India, is made from strained yogurt, saffron, cardamom, nutmeg and sugar and sometimes fruits such as mango or pineapple.

In North America, strained yogurt is commonly called “Greek yogurt” and in Britain as “Greek-style yogurt”. In Britain the name “Greek” may only be applied to yogurt made in Greece.[46]

Beverages

Ayran, doogh (“dawghe” in Neo-Aramaic) or dhallë is a yogurt-based, salty drink. It is made by mixing yogurt with water and (sometimes) salt.

Lassi is a yogurt-based beverage that is usually slightly salty or sweet, and may be commercially flavored with rosewater, mango or other fruit juice. Salty lassi is usually flavored with ground, roasted cumin and red chilies, may be made with buttermilk.

An unsweetened and unsalted yogurt drink usually called simply jogurt is consumed with burek and other baked goods. Sweetened yogurt drinks are the usual form in Europe (including the UK) and the US, containing fruit and added sweeteners. These are typically called “drinkable yogurt”. Also available are “yogurt smoothies”, which contain a higher proportion of fruit and are more like smoothies.

Plant-milk yogurt

A variety of plant-milk yogurts appeared in the 2000s, using soy milk, rice milk, and nut milks such as almond milk and coconut milk. These yogurts are suitable for vegans, people with intolerance to dairy milk, and those who prefer plant-based products.[47]

Homemade

Commercially available home yogurt maker

Yogurt is made by heating milk to a temperature that denaturates its proteins (scalding), essential for making yogurt,[48] cooling it to a temperature that will not kill the live microorganisms that turn the milk into yogurt, inoculating certain bacteria (starter culture), usually Streptococcus thermophilus and Lactobacillus bulgaricus, into the milk, and finally keeping it warm for several hours. The milk may be held at 85 °C (185 °F) for a few minutes, or boiled (giving a somewhat different result). It must be cooled to 50 °C (122 °F) or somewhat less, typically 40–46 °C (104–115 °F). Starter culture must then be mixed in well, and the mixture must be kept undisturbed and warm for some time, anywhere between 5 and 12 hours. Longer fermentation times produces a more acidic yogurt. The starter culture may be a small amount of live (not sterilized) existing yogurt or commercially available dried starter culture.

Milk with a higher concentration of solids than normal milk may be used; the higher solids content produces a firmer yogurt. Solids can be increased by adding dried milk.[49] The yogurt-making process provides two significant barriers to pathogen growth, heat and acidity (low pH). Both are necessary to ensure a safe product. Acidity alone has been questioned by recent outbreaks of food poisoning by E. coli O157:H7 that is acid-tolerant. E. coli O157:H7 is easily destroyed by pasteurization (heating); the initial heating of the milk kills pathogens as well as denaturing proteins.[50] The microorganisms that turn milk into yogurt can tolerate higher temperatures than most pathogens, so that a suitable temperature not only encourages the formation of yogurt, but inhibits pathogenic microorganisms. Once the yogurt has formed it can, if desired, be strained to reduce the whey content and thicken it.

Probiotic yogurt (labeled as “live yogurt” or “active yogurt”) is yogurt pasteurized to kill bacteria, with Lactobacillus added in measured units before packaging.

Yogurt probiotic drink is a drinkable yogurt pasteurized to kill bacteria, with Lactobacillus added before packaging.

Research suggests Homemade Yogurt[54] and Live Yogurt[55][56] are much more beneficial than ‘Heat Treated Fermented Milk’ (Pasteurized Yogurt). European Food Safety Authority has confirmed the probiotic benefits of Yogurt containing 108 CFU ‘live Lactobacilli’ [57]

Lactose intolerance

Lactose intolerance is a condition in which people have symptoms due to the decreased ability to digest lactose, a sugar found in dairy products. In 2010, the European Food Safety Authority (EFSA) determined that lactose intolerance can be alleviated by ingesting live yogurt cultures (lactobacilli) that are able to digest the lactose in other dairy products.[57] The scientific review by EFSA enabled yogurt manufacturers to use a health claim on product labels, provided that the “yogurt should contain at least 108 CFU live starter microorganisms (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus) per gram. The target population is individuals with lactose maldigestion.”[57]

Gallery

Doogh is a Turkish savory yogurt-based beverage, traditionally served cold and is sometimes carbonated and seasoned with mint and salt.

Skyr is an Icelandic cultured dairy product, similar to strained yogurt traditionally served cold with milk and a topping of sugar

Tart flavored frozen yogurt is a frozen dessert made with yogurt and sometimes other dairy products including non-dairy products. It is usually more tart than ice cream, as well as lower in fat. It is different from ice milk and conventional soft serve.

^Alcock, Joan Pilsbury (2006). Food in the Ancient World. Greenwood Publishing Group. p. 83. ISBN9780313330032. Curdled milk (oxygala or melca), probably a kind of yogurt, was acceptable because it was easier to digest. Even so, it was still to be mixed with honey or olive oil. Columella gave instructions on how to make sour milk with seasoning into …

^ abHoffman, Susanna (2004). The Olive and the Caper: Adventures in Greek Cooking. Workman Publishing. p. 471. ISBN9780761164548. …something like yogurt was known to Greeks since classical times—a sort of thickened sour milk called Pyriate or oxygala. Oxi meant “sour” or “vinegar”; gala, “milk”. Galen says that Oxygala was eaten alone with honey, just as thick Greek yogurt is today.

^ abAdamson, Melitta Weiss (2008). Entertaining from Ancient Rome to the Super Bowl: An Encyclopedia [2 volumes]: An Encyclopedia. ABC-CLIO. p. 9. ISBN9780313086892. Oxygala, however, a form of yogurt, was eaten and sometimes mixed with honey. Ancient Greek and Roman cuisine did not rely on non-cultured milk products, which can be explained in part because without refrigeration milk becomes sour …

^The Natural History of Pliny, tr. John Bostock, Henry Thomas Riley, London: Bell, 1856–93, Volume 3, p. 84: “It is a remarkable circumstance, that the barbarous nations which subsist on milk have been for so many ages either ignorant of the merits of cheese, or else have totally disregarded it; and yet they understand how to thicken milk and form therefrom an acrid kind of milk with a pleasant flavor”.